<p>The martensitic transition sequence and microstructure evolution in a homogenized Fe–15Mn alloy under thermal cycling, involving a thermal body-centered cubic α′-martensite, hexagonal close-packed <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\upvarepsilon$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">ε</mi> </math></EquationSource> </InlineEquation>-martensite, and face-centered cubic γ-austenite, were characterized by neutron diffraction and transmission electron microscope. The <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\upvarepsilon$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">ε</mi> </math></EquationSource> </InlineEquation> <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$\to$</EquationSource> <EquationSource Format="MATHML"><math> <mo stretchy="false">→</mo> </math></EquationSource> </InlineEquation> α′ transition is observed for the first time during heating. Upon cooling, γ → <InlineEquation ID="IEq5"> <EquationSource Format="TEX">$\upvarepsilon$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">ε</mi> </math></EquationSource> </InlineEquation> and γ <InlineEquation ID="IEq6"> <EquationSource Format="TEX">$\to$</EquationSource> <EquationSource Format="MATHML"><math> <mo stretchy="false">→</mo> </math></EquationSource> </InlineEquation> α′ transitions occur concomitantly. The transition rate of the γ <InlineEquation ID="IEq7"> <EquationSource Format="TEX">$\to$</EquationSource> <EquationSource Format="MATHML"><math> <mo stretchy="false">→</mo> </math></EquationSource> </InlineEquation> <InlineEquation ID="IEq8"> <EquationSource Format="TEX">$\upvarepsilon$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">ε</mi> </math></EquationSource> </InlineEquation> is higher than that of the γ <InlineEquation ID="IEq9"> <EquationSource Format="TEX">$\to$</EquationSource> <EquationSource Format="MATHML"><math> <mo stretchy="false">→</mo> </math></EquationSource> </InlineEquation> α′ in the early stage of the phase transition. The Fe–15Mn alloy exhibits a pronounced volume effect of phase transition (1.6% for <InlineEquation ID="IEq10"> <EquationSource Format="TEX">$\upvarepsilon$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">ε</mi> </math></EquationSource> </InlineEquation> → γ, 1.8% for α′ → γ, and 4.2% for <InlineEquation ID="IEq11"> <EquationSource Format="TEX">$\upvarepsilon$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">ε</mi> </math></EquationSource> </InlineEquation> → α′), which induces an obvious lattice mismatch. The sharp increase in the volume fraction of <InlineEquation ID="IEq12"> <EquationSource Format="TEX">$\upvarepsilon$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">ε</mi> </math></EquationSource> </InlineEquation>-martensite after thermal cycling is attributed to the formation of abundant stacking faults and the pre-existing α′-martensite within the alloy.</p>

Structural evolution in Fe–15Mn steel under thermal cycling

期刊论文
发表日期：

2026年4月11日

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Li-Ying Sun,
Hui-Lan Huang,
Sergey Viktorovich Sumnikov,
Roman Nikolaevich Vasin,
Ivan Anatolyevich Bobrikov,
Gizo Dasmirovich Bokuchava,
Anatoly Mikhailovich Balagurov,
Natalia Yurievna Tabachkova,
Bo-Lin Qu,
Rustam Mannapovich Saidov,
Bei-Yue Ma,
Fu-Xing Yin,
Igor Stanislavovich Golovin

摘要

The martensitic transition sequence and microstructure evolution in a homogenized Fe–15Mn alloy under thermal cycling, involving a thermal body-centered cubic α′-martensite, hexagonal close-packed $\upvarepsilon$ $ε$ -martensite, and face-centered cubic γ-austenite, were characterized by neutron diffraction and transmission electron microscope. The $\upvarepsilon$ $ε$ $\to$ $\to$ α′ transition is observed for the first time during heating. Upon cooling, γ → $\upvarepsilon$ $ε$ and γ $\to$ $\to$ α′ transitions occur concomitantly. The transition rate of the γ $\to$ $\to$ $\upvarepsilon$ $ε$ is higher than that of the γ $\to$ $\to$ α′ in the early stage of the phase transition. The Fe–15Mn alloy exhibits a pronounced volume effect of phase transition (1.6% for $\upvarepsilon$ $ε$ → γ, 1.8% for α′ → γ, and 4.2% for $\upvarepsilon$ $ε$ → α′), which induces an obvious lattice mismatch. The sharp increase in the volume fraction of $\upvarepsilon$ $ε$ -martensite after thermal cycling is attributed to the formation of abundant stacking faults and the pre-existing α′-martensite within the alloy.